I. Field of the Invention
The present invention relates generally to anti-theft systems for vehicles. More particularly, the present invention relates to a brake-engaging system that utilizes conventional vehicle parts to modify an existing hydraulic brake system.
II. Description of the Relevant Art
Anti-theft devices have been known for almost as long as the motor vehicle has been in use. Accessory locks for early vehicles such as the Ford Model "T" were designed to lock the steering wheel and ignition system.
Many of these early anti-theft devices were used to lock vehicle transmissions thereby preventing the engine from starting and subsequent movement of the vehicle. For example, U.S. Pat. No. 1,269,318 issued to Schneider shows an automobile lock for locking the teeth of a flywheel to prevent its rotation. Also disclosing a method of locking a flywheel is U.S. Pat. No. 1,706,352 issued to Sequirant. Relatedly, U.S. Pat. No. 1,298,283 issued to Bigelow locks the transmission gears of a vehicle. The transmission is also locked in U.S. Pat. No. 1,721,013 issued to Fortin.
Some of these early anti-theft devices provided methods for locking the wheels. For example, U.S. Pat. No. 1,231,125 issued to Cahusac teaches an electromechanical system for locking automobile wheels. A system for engaging and locking a wheel rim is disclosed in U.S. Pat. No. 1,303,110 issued to Pfleeger. A method of locking the wheels is also disclosed in U.S. Pat. No. 1,638,062 issued to Scherer.
Other systems have been developed that act on the braking system of the vehicle to thereby fix the vehicle in place. An early, relatively primitive electrical braking anti-theft system is disclosed in U.S. Pat. No. 1,230,449 issued to VanDerbeck. Vacuum control of the parking brake of a vehicle is disclosed in U.S. Pat. No. 3,552,518 issued to Aidner. Similarly, an anti-theft system using a vacuum chamber that is evacuated to set the brakes is disclosed in U.S. Pat. No. 3,669,210 issued to Haefner. Air pressure is used for engagement of the brakes of a vehicle in U.S. Pat. No. 4,732,018 issued to Crosby.
Almost all vehicles made in the last fifty years or so rely on hydraulic fluid systems for braking. In U.S. Pat. No. 4,765,362 issued to Baruch, an anti-theft system that utilizes hydraulic fluid is disclosed. According to this system, a special valve having various inlet and outlet ports for hydraulic fluid is used in a hydraulic system to lock the steering and brakes of a vehicle. The system utilizes a foot operated brake to pressurize the lines. When the valve is rotated in its housing by a key, it functions as a one-way valve, preventing the back-flow of brake fluid once the pressure on the brake pedal is relieved.
For all of this creativity, an efficient, easily attached, sure-locking vehicle anti-theft system is wanting. The above-described systems suffer either from excessive complexity, cost or are simply impractical for application to modern vehicles.